1. Field of the Invention
The invention relates to the process of thermal transfer printing, especially multicolored printing forms or offset printing forms, using a narrow ribbon as transfer film. More specifically, the invention relates to a process of thermal transfer printing which optimizes the provision of thermal transfer material and correctly makes available different materials for the respective purpose at the correct time.
2. Description of the Related Art
The process of thermal transfer has been known for years. In principle, a substrate which may be the final substrate or an intermediate substrate is brought into contact with an ink film arranged on a carrier and the ink film is transferred by thermal action to the substrate in points or dots to form the image on the substrate.
Several colors may also be applied successively by using different colored films so that color printing can be realized in his way. If the substrate is an intermediate substrate, the finished multicolored image is then transferred in a further step to the target substrate. Further, a printing form may also be coated to form an image by a suitable polymer. For example, if the printing form base is hydrophilic and therefore does not accept ink, the image-carrying parts are transferred to this printing form as a positive by thermal transfer and are then hydrophobic, that is, ink-accepting.
A prior art process for printing via thermal transfer is disclosed in German Patent DE 44 30 555. In this process, the thermal transfer film is constructed as a narrow ribbon. The problem in this method consists in that the thermal transfer ribbon must be changed after every generated image or after a few generated images. Further, this reference does not indicate how thermal transfer ribbons composed of different materials can be used electively for different requirements, which would be desirable.